Rheumatoid arthritis (RA) is characterized by hyperplasia of synovial membrane and bone destruction. Fibroblast-like synoviocytes play an important role in the pathogenesis of rheumatoid arthritis because of their proliferation and secretion of an impressive array of cytokines/chemokines, adhesion molecules, and proteases, which result in the progressive bone and joint destruction. Synovectomv is a surgical approach to remove the inflammatory synovium, ameliorate the inflammation and delay the progress of joint destruction. An efficient medically-induced programmed cell death (apoptosis) in the inflammatory synovium might play a role similar to synovectomy but without surgical tissue damage. The proposed research project focuses on developing the "FasL gene scalpel" for the replacement of the synovectorny for the treatment of rheumatoid arthritis and other arthropathies. This project simplifies the current problems of gene delivery, gene target and gene expression regulation in human gene therapy. The induction of apoptosis in the inflammatory synoviocytes is the main purpose of FasL gene transfer intra-articularly. A transient, localizable, immune tolerance and dose dependent gene transfer may be achieved by a direct intra-articular injection of the FasL gene carried by a suitable vector which infects synoviocytes but not chondrocytes in cartilage. To carry out this purpose, they have investigated the effects of FasL gene transfer on the human RA synovium. The results showed that the fibroblast-like synoviocytes can be infected by adenovirus-FasL as well as undergo apoptosis after infection in a dose-dependent fashion and that the inflammatory synovium from RA patients can be eliminated in situ in a RA-SCID mouse model by a repeated local administration of adenovirus vector mediated FasL gene transfer. In this application, they propose to produce an adenovirus carrying human Fas Ligand gene and GFP in the same vector to examine whether FasL gene transfer in human RA synovium in SCID mouse model in vivo through the mechanism of "bystander effects." If the bystander effects exist in FasL gene transfer into synovium, it would be possible to carry out a therapeutic level of gene transfer with non-viral vector and lower dosage of DNA. They are going to investigate the possible side effects involved in FasL gene transfer into synovial fibroblasts and synovium, such as induction of pro-inflammatory cytokines/chemokines production as well as their correlation with Fas/FasL interaction, in order to find an approach to control them. They will identify the effects of the long term, multiple FasL gene transfer on the viability and metabolism of chondrocytes in vivo. This is an important factor to evaluate the clinical potential of the FasL gene scalpel. The above studies could elucidate clinical potential and possible side effects of FasL gene transfer intra-articularly, and have a high likelihood of being translated into a novel approach for treating arthritis patients at the inflammatory site. The long-range goals are the development of a novel therapeutic approach--"Gene Scalpels" for arresting inflammatory synovium at an early stage of arthritis by intra-articular administration of an apoptosis inducer, such as FasL, using a suitable vector system, which may replace synovectomy for some arthritis patients.